Wet wipes, typically a nonwoven material (i.e., a substrate) that is impregnated with a cleaning lotion, are frequently used for personal hygiene tasks such as cleanup after urination or defecation (i. e. perianal cleaning). Wet wipes have found particular utility in helping a caregiver with cleaning tasks related to changing an absorbent article, such as an infant diaper. The cleaning lotion is often an emulsion comprising an oily phase (e. g. an emollient and perfume components), an emulsifier or surfactant and an aqueous phase that comprises further additives such as a rheological modifier. Such lotions facilitate mechanical removal of residues by the substrate by helping to disperse solid matter that is not mechanically removed. Residual lotion components can also provide skin care benefits.
However, improvements are still needed. For example, much of the lotion that is impregnated into the substrate in the manufacturing process is not available to facilitate cleaning. As a result, the wet wipe may also not release enough cleaning lotion to satisfactorily disperse fecal matter. Users of wet wipes react to insufficient lotion negatively. Products that don't deliver enough cleaning lotion are seen as having poor value, having a rough texture so they are harsh (lotion also acts as a lubricant) and not performing well because cleaning is seen as difficult (also seen as resulting from poor lubricity). A particular source of such reduced lotion delivery is lotion drainage from the top of a stack of wet wipes during storage. In this situation, a wipe may be fully saturated immediately after packaging but, with the passage of time, lotion may drain from the wipe and pool in the bottom of the container. As a result, a portion of the wipes, frequently the first wipes encountered when a package is opened, may be drier than is desired for optimal performance.
The art has approached improvement of wet wipe lotion formulation on several fronts: variation of surfactant type and content, variation of emollient type, variation in the preservative system and addition of agents aimed at having an effect on the skin (e.g., botanicals or pharmaceutically active materials). In one example, compositions for non perianal personal cleaning tasks (e.g., removal of dirt, oil and other matter, such as makeup, from the skin or hair) are known. One group of such compositions relies on physical abrasion by suspended particulate matter. However, such products typically are thickened (e.g., in a gel or cream form) and, thus, are not suitable for use with a wet wipe because they have insufficient fluidity to disperse fecal solids that are not mechanically removed by wiping with the wipe. Such thickened compositions also make impregnating the substrate with a cleaning lotion at commercially viable production rates difficult. The art has also considered the balance of ease of lotion impregnation into a substrate and cleaning efficiency by providing lotions with a lower viscosity at elevated temperature (˜50° C.) than at room temperature (˜25° C.). However, the art has not fully considered the effect of lotion composition on the various requirements a cleaning lotion should satisfy (e. g. ease of lotion impregnation into a substrate, stability of the lotion loading on the substrate during storage and lotion release from the substrate during use).